$-3\dfrac{1}{2} \div \dfrac{-5}{8} = $
Answer: Let's start by converting the mixed number to a fraction. $\phantom{=}-3\dfrac{1}{2}\div\dfrac{-5}{8}$ $=-\dfrac{7}{2}\div\dfrac{-5}{8}$ $=-\dfrac{7}{2}\cdot\dfrac{8}{-5}~~~~~~~\text{multiply by the reciprocal}$ $=-\dfrac{7}{{1}\cancel{2}}\cdot \dfrac{{4}\cancel{8}}{-5}$ $=-\dfrac{7}{1}\cdot\dfrac{4}{-5}$ $=-\dfrac{28}{-5}$ $=\dfrac{28}{5}\text{ or }5\dfrac35$